California Wildfires, California Department of Forestry and Fire Protection (Cal Fire)
The fire at the Shahid Tondgooyan refinery in the south of the capital Tehran was still not completely extinguished on Thursday, a day after it broke out.
According to media reports, huge clouds of smoke could be seen again in several parts of the Iranian capital city, reports dpa news agency.
On Wednesday evening, it was said that the fire was under control.
A spokesperson for the plant however announced that a decision had been made during the night to let the exploded gas oil pipeline burn out.
Ninety-five per cent of it had already burnt out, and firefighters and rescue workers could start clearing it up in the next few hours, spokesman Shaker Khafaei told state broadcaster.
Khafaei reiterated that there were no deaths or injuries in the fire, and that the cause of the incident and the extent of the damage would be thoroughly investigated after the extinguishing work.
So far, it is assumed that there was a technical error and it is not an act of sabotage.
The spokesperson also said that the plant would be put back into operation sooner than planned.